Peson not filing ITR 4 (u/s 44AD) for continuous period of 5 year, can't file again ITR 4 for 5 year from year in which he file Other ITR.
So, in your case, you not filed ITR 4 for continuous period of 5 years,( Assume that you not filed ITR4 in earlier year before A.Y 2017-18 (i.e 2016-17,2015-16 ect.) So, you can't file ITR 4 up to 5 year i.e A.Y 19-20,20-21...